Re: UEFI/"BIOS" booting, was Re: USB Install Fails, Complains about CD-ROM

[Pascal Hambourg <pascal@plouf.fr.eu.org>]

Le 15/05/2018 à 03:23, David Wright a écrit :
> In this particular instance (the Lenovo), its PDF says:
(...)
>      The default boot mode for your computer is UEFI mode. If you need to
>      install a legacy operating system, such as Windows (that is, any operating
>      system before Windows 8)

This is so wrong. Windows has supported EFI since Vista.

> AIUI what's unspecified is what you choose to put in the code section
> of the MBR. In my case, and probably for most people here, it will be
> Stage 1 of Grub.

Note : "stage 1" is a GRUB legacy thing. GRUB 2 calls it "boot image".

> And if one has any sense, that will be pointing to a
> BIOS boot partition, which is one of the first things I set up on a
> GPT disk so that I can use it in my old BIOS machines. It makes things
> far more bullet-proof if Grub knows there's a safe place to put its
> later Stages. I suspect that systems without ones are likely to be the
> ones causes much of the reported trouble.

Moreover, GRUB BIOS cannot be installed without embedding (in a BIOS 
boot partition or any other suitable location) when the /boot filesystem 
is anywhere else than a plain partition (LVM, RAID, crypto...) or a 
filesystem type which may move block around such as btrfs, defeating the 
hardcoded blocklists.